Chlorination of poly

Halogenatlon. Poly(2,6-dimethyl- and 2,6-diphenyl-l,4-phenylene ether) can be aryl-brominated simply by exposure to a bromine solution no catalyst is required.6 In fact, the use of Lewis acid catalysts to promote the chlorination of poly(2,6-dimethy1-1,4-phenylene ether) leads to substantial degradation of the molecular weight of the chlorinated products.7 Membranes produced from ring brominated PPO (40% wt Br) exhibited enhanced permeability to CHi and CO2 and proved to be more selective in separating CH4/CO2 mixtures.8... 

Chloromethyl polystyrene (Merrifield resin) has been prepared by chloro-methylation of polystyrene [23,27,53,54], by copolymerization of 4-chloromethylsty-rene with styrene [20,26,55,56], and by chlorination of poly(4-methylstyrene) [57,58], Aminomethyl polystyrene is most conveniently prepared by direct amidomethylation of polystyrene with (hydroxymethyl)amides or (halomethyl)amides under acidic conditions followed by hydrolysis [59-62], but it has also been prepared directly from chloromethyl polystyrene ([63,64] see also Section 10.1.1.1). 

Free radical chlorination of poly(phenylsilane) to produce poly (chlorophenylsilane) and then substitution with MeOFI or MeMgBr... 

The chlorination of poly(vinyl chloride) (PVC) and the use of unsaturated polymers for further reaction is presented in this section only as an example of some common techniques used. The use of unsaturated polyesters is described in Vol. II of this series [13],... 

A study was conducted on solution chlorination of poly(vinyl chloride) in the presence of free radicals generated from azobisisobutyronitrile. The reaction appears to proceed in two stages. The first takes place until 60% of all the CH2 groups have reacted. After that, in the second stage... 

Chlorination of poly(vinylidene chloride) can be carried out with sulfuryl chloride using azobisisobutyronitrile. The reaction appears to proceed in three steps ... 

Chlorinations of poly(p-methyl styrene) are somewhat more selective for the pendant methyl groups and result in di- and tri-substitutions at the p-methyl position. Only small amounts of chlorine are introduced into the polymer backbones. Substitutions at the backbones, however, are possible with the use of SO2CI2 as the chlorinating agent. In this case, half of the chlorines still replace the methyl hydrogens, but the other half replace hydrogens on the backbone. 

Discuss chlorination of poly(vinylidine chloride) and poly(vinyl fluoride). 

Halogenation and hydrohalogenation of elastomers have been reported extensively in the literature [26]. The main problems with these reactions are the cyclization and chain scission that occur parallel to the halogenation reaction. These introduce difficult problems in the characterization of the resulting products. Despite these problems, several products have been prepared and commercialized. Chlorination of poly(l, 4-butadiene) to prepare a product similar to poly(vinyl chloride) has been reported by several workers [27]. This process had extensive side reactions and chain degradation. The chlorination of butyl rubber and conjugated diene-butyl rubbers gives end products that are used in the tire industry as inner liners for air retention. 

Procedures for commercial chlorinations of poly(vinyl chloride) vary. Low temperature chlorinations are done on aqueous dispersions of the polymers that are reacted with chlorine gas in the presence of swelling agents, like chloroform. These are light catalyzed reactions, usually carried out at about 50°C. They result in substitutions of methylene hydrogens [158, 159]. 

Chlorination of poly(vinyl fluoride) yields a product with 40-50% chlorine content [158]. Fluorination of poly(vinylidene fluoride) was reported [160]. When mixtures of fluorine and nitrogen gases are used, the reactions are limited by the amount of diffusion of fluorine into the polymer network. X-ray photoelectron spectroscopy shows presence of -CF2-, -CHF-, and -CH2-groups in the product [161]. 

Chlorination of poly(vinyl chloride) destroys the regularity of the tacticity. Dor-restijn et al. [123] executed chlorination in two different ways. First, pol>tvinyl chloride) was chlorinated in solution so that no preference existed for the kind of hydrogen atom which was replaced by chlorine atoms the tacticity of the polymer molecules is destroyed more or less completely. Second, the polymer was chlorinated in powder form in this case there is a large preference for the amorphous parts, whereas the crystalline parts are mudi less available for chlorination and remain more or less intact Even if the polymer is attacked prrferentially at the isotactic sequences, the tendency to form gels will decrease, as the [nresence of an even number of isotactic sequences in between syndiotactic sequences causes an enormous increase in the crystallinity of polyfviny chloride) [82,84]. Dorrestijn et al. showed that chlorination had a dramatic influence on the tendency to form gels in the case of solution chlorination, whereas powder chlorination had only a minor effect despite much higher chlorine contents. 

Vinyl chloride, head-to-head Single Tg I had 23.5—56.6 wt% acrylonitrile II was made from chlorination of poly (1,4-butadiene) Cowie et al. (1992d)... 

Figure 7. Chlorination of poly(ether-urethane) prosthesis.

Poly(vinyl chloride) has received rather little attention over the past two years, though there is still some interest in replacing the chlorine of poly(vinyl chloride) with other substituents. Hence, reductive dechlorination with LiAlHj has been used... 

Depending on the conditions used, various products may be obtained by the post-chlorination of poly(vinyl chloride). Two types of product are made commercially, one by chlorination at low temperature and one by chlorination at high temperature. 

Chlorination has been carried out on many other polymers as well as PE the chlorinations of PVC, polypropylene, fluorinated polymers, etc, have been the subject of numerous studies. The chlorination of poly(vinylidene fluoride) has been carried out in boiling CCI4 suspension products containing 26% of chlorine were obtained, and exhibit very interesting properties. 

Free radical chlorination of poly(phenylsilane) produces poly(chlorophenylsilane) These chlorinated polymers can be substituted with a variety of nucleophiles such as MeOH or MeMgBr with high selectivities. The spectroscopic properties of these materials are extremely sensitive to the nature of the substituent attached to the polymer backbone. The UV properties of a series of polysilanes containing Si-H, Si-Cl, Si-R and Si-OR functionalities are reported. The absorption maximum of poly(phenylsilane) appears at 294 ran (esi-si = 2489 cm-iM 0 whereas that of poly(methylphenylsilane) appears at 328 nm (esi-si = 4539 cm-iM-i). The absorption spectra of poly(metiioxyphenylsilane) are red shifted considerably relative to the other polymers (X = 348 nm, esi-si = 2710 cm- M-O. These substituent effects are likely due both to conformational as well as electronic perturbations on tfie Si-Si backbone chromophore. 

The effect of substitution reactions on the number average molecular weight (M ) of the polymer was investigated by vapor pressure osmometry. Chlorination of poly(phenylsilane) results in a decrease in the degree of polymerization (DP) from about 40 to 25 silicon atoms (Table I). Subsequent substitution of Si-Cl with Si-OMe further degrades the polymer to less than 15 monomer units. Methylation of poly(chlorophenylsilane) with MeMgBr affords, upon purification, a 41% yield of poly(methylphenylsilane) of approximately the same de ee of polymerization as the original poly(phenylsilane). 

Although the introduction of halogen-containing substituents into linear polysilanes have been reported,(55, 41, 45) further modification of structure and electronic properties of Aese polysilanes have not been extensively studied. We have recently reported that free-radical chlorination of poly(phenylsilane) with CCI4 provides a facile synthesis of poly(chlorophenylsilane), a versatile synthon for the preparation of a variety of functionalized poly(phenylsilane).(59) TTiis new synthetic capability has allowed us to investigate the influence of polymer substituent on the electronic properties of poly silanes. 

Hall developed a mild method for chlorination of poly (phenylene oxide)s exclusively on the backbone which gave a maximum of only one chlorine per unit. The chlorination reaction utilized phosgene or thionyl chloride in the presence of a sulfoxide. ... 

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